Evidence of internal electric fields in GaInP2 by scanning capacitance and near-field scanning optical microscopy

GaInP2 is studied in cross section with the scanning capacitance and near-field scanning optical microscope. Our study shows significant differences in the electronic and optical properties between ordered single- and two-variant GaInP2. In single-variant samples, spatially uniform capacitance signal, photoluminescence intensity, and band gap are observed. In contrast, a spatially nonuniform capacitance signal, photoluminescence intensity, and band gap are observed in samples with nominally uniform doping. Imaging of the same regions by scanning capacitance and near-field scanning optical microscopes demonstrates that the photoluminescence (observed by the near-field scanning optical microscope) comes only from the n-type-like regions (observed by the scanning capacitance microscope) in lightly doped (n-type) two-variant GaInP2. The local capacitance and photoluminescence measurements can be explained by the presence of internal electric fields in two-variant GaInP2.